1. Field of the Invention
The present invention relates to a testing procedure for determining frequency distortions and group delay time distortions of a test object, for example, a telecommunication link which is fed with a test pulse and where the deformation caused by the test object is evaluated.
2. Description of the Prior Art
In existing procedures, the group delay time of a test object is determined by using a procedure, named after Nyquist, by determining the phase displacement of the envelope of a modulated sinusoidal carrier which also produces frequency distortion information. This procedure will result in accurate test levels; it is however rather time consuming and complicated to perform a test.
For simplified pass/reject decisions with respect to group delay time and frequency distortion measurements in the low frequency voice communication band, it is also known to use a so-called PAR process, in which a pulse sequency is manually introduced to a transmission link and an attempt is made to draw conclusions with regard to the quality of the transmission line by measuring the pulse degradation by determining the ratio between peak and average values. Several influence quantities, however, effect the test results, which differently influence the various types of modulations in data transfer. This restricts the potential value of this simple process.